Apparatus for physiological investigation

ABSTRACT

Accelerometer transducer apparatus, of the type which is resistive, complete balanced bridge, unbonded strain gage, is positioned in engagement with the chest wall of a subject in the region of the heart. The accelerometer transducer has a primary response in a direction substantially normal to the chest of the subject. Sensing mechanism which senses frequencies in the range of between two and thirty cycles per second is connected to the accelerometer transducer, the signal output thus being a function of the precordial vibrations associated with the chest wall of the subject.

United States Patent Vielhauer [4 1 Oct. 3, 1972 [54] APPARATUS FORPHYSIOLOGICAL 3,076,452 2/1963 Rothe ..128/2.05 B INVESTIGATION3,187,098 6/1965 Farrar et a1 12812.05 P .....l28/2.05 P 72 Inventor.Harold o. vielhauei, 1359 Fudge 3,154,006 10/1964 K Drive Xenia, Ohio45385 2,837,082 6/1958 Eliott et a1 ..128/2.05 B

[22] Filed: June 29, 1970 Primary Examiner-William E. Kamm [21] AppL NeZ50,542 Attorney-Jacox & Meckstroth Related us. Application Data 57]ABSTRACT [63] Continuation of Ser. No. 586,117, Oc Accelerometertransducer apparatus, of the type 1966, abandoned- I which is resistive,complete balanced bridge, un-

bonded strain gage, is positioned in engagement with U-So P the chest ofa ubject in the region of the heart [51] Int. Cl. ..A6lb 5/02 Theaccelerometer transducer has a primary response [58] i 'g;g 2%5 & 2 3 53 in a direction substantially normal to the chest of the subject.Sensing mechanism which senses frequencies 3 in the range of between twoand thirty cycles per second is connected to the accelerometertransducer,

the signal output thus being a function of the precor- [56] Referemsc'ted dial vibrations associated with the chest wall of the UNITEDSTATES PATENTS j 3,405,288 10/ 1968 Dittrich ..128/2.05 P 5 Claims, 3Drawing Figures l0 ACCELEROMETER PATENTEDncra m2 3.695253- INDICATOR l0ACCELEROMETER APPARATUS OF THIS INVENTION ELECTROCARDIOGRAPH FIG-2IINDICATORI INVENTOk HAROLD e. VIELHAUER IOACCELEROMETER ATTORNEYAPPARATUS FOR PHYSIOLOGICAL INVESTIGATION RELATED APPLICATION Thisapplication is a continuation of my pending application, Ser. No.586,117, filed Oct. 12, 1966, now abandoned.

BACKGROUND OF THE INVENTION Various types of apparatus have beendeveloped and used for physiological investigation. In the past,apparatus which has been used for investigation of heart action or bloodpressure has required attachment of a portion of the apparatus to thesubject being investigated or insertion of a portion of the apparatusinto the subject. Of course, such requirements have been objectionable.

Furthermore, prior to this invention, satisfactory means forcontinuously monitoring or indicating or measuring blood pressure havenot been available.

Also, most types of apparatus for cardiovascular investigation have beenlarge and bulky and are thus objectionable.

An object of this invention is to provide apparatus which may be used invarious types of physiological investigation, or determination, orobservation, or the like.

Another object of this invention is to provide apparatus which iscapable of continuously or instantaneously monitoring, measuring orindicating cardiovascular forces.

Another object of this invention is to provide apparatus which iscapable of continuously or instantaneously monitoring, measuring, orindicating the blood pressure of a human subject or other animal.

Another object of this invention is to provide such apparatus which iscapable of detecting exact forces in the cardiovascular system of asubject.

Another object of this invention is to provide such apparatus which maybe used without attachment to the subject.

Another object of this invention is to provide such apparatus which maybe used without the insertion of any portion thereof into the subject.

Another object of this invention is to provide such apparatus which canbe very small in physical size and weight.

Another object of this invention is to provide such apparatus which maybe used while the subject is moving, working, or performing certaintypes of activity.

Other objects and advantages reside in the construction of theinvention, combinations thereof, the method of manufacture, and the modeof operation, as will become more apparent from the followingdescription.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic type of viewillustrating apparatus of this invention in use with a subject who ishorizontally disposed.

FIG. 2 is a diagrammatic type of view illustrating apparatus of thisinvention in use with a subject, the upper portion of whom is verticallydisposed and who may be performing certain types of activity.

FIG. 3 shows a typical waveform obtained by the apparatus of thisinvention and a typical waveform obtained by an electrocardiograph, eachwaveform representing one heart beat of the subject.

Referring to the drawing in detail, apparatus of this inventioncomprises a transducer in the form of an accelerometer 10. Theaccelerometer 10 is positioned in engagement with a chest 12 of asubject, as shown in FIGS. 1 and 2. In FIG. 1 the chest 12 is shown asbeing substantially horizontal with the accelerometer 10 restingthereupon. In FIG.- 2 the chest 12 is shown as being substantiallyvertical. Means (not shown) of any suitable type may be used, if desiredor necessary, to retain the accelerometer 10in the desired position inengagement with the chest 12.

The accelerometer 10 may be small in physical dimensions, in comparisonto the dimensions of the chest 12. An accelerometer 10 which has beenfound to be satisfactory has physical dimensions less than two inches inlength, less than one-half inch in width, and

less than one-half inch in height. However, accelerometers of variousother dimensions are also satisfactory.

The accelerometer 10 which has been found to be .very satisfactory isone which has a weight-of 'considerably less than 50 grams. Theaccelerometer 10 is one which is electrically energizable and/or whichprovides an output in the form of electrical signals.

Preferably, the accelerometer 10 has a rating of between 1 G and 6 G.That is, the accelerometer 10 may be one which is capable of producingsatisfactory output signals when subjected to independent forces up toone times the force of gravity (1 G) -or the accelerometer 10 may have acapacity greater than one times the force of gravity, but preferably,not in excess of 6 times the force of gravity (6 G). The accelerometer10 is, preferably, one which has a primary response when moved in adirection substantially normal to the chest 12 with which theaccelerometer 10 is in engagement.

Satisfactory results have been obtained with, for example, anaccelerometer transducer identified as: 4 G Statham Accelerometer (F-4,340, 11v maximum), (resistive, complete balanced bridge, unbonded straingage). The accelerometer is directionally sensitive and its response totransverse acceleration is, preferably, not more than 0.02 G per G andits non-linearity and hysteresis are not more than plus or minus 1percent of full scale.

The accelerometer 10 may be positioned in engagement with the chest wallat any portion thereof. However, preferably, to obtain maximum amplitudeof signals produced, the accelerometer 10 is positioned in engagementwith the chest 12 in the location of the apex beat of the heart.

The accelerometer 10 is connected by suitable electrical conductor means14 to any suitable apparatus 18 which is capable of providing agraphical or an instantaneous reading. For example, the apparatus 18 maybe a graphic recording device, or an oscilloscope, or an electricindicating instrument or the like or any other suitable apparatus,device or instrument.

Preferably, the apparatus 18 is one which senses only signals which havea frequency of between 2 to 30 cycles per second. Thus, the signalssensed are only those which are related to the mechanical activity ofthe heart. Therefore, other vibrations, such as chest sounds andrespiration, which normally occur at frequencies which are not withinthe range of 2 to 30 cycles have insignificant effect upon the signalssensed by the apparatus 18.

The accelerometer is capable of producing a signal which is a functionof the acceleration forces to which it is subjected. Thus, the signaltransmitted to the apparatus 18 which is indicated or recorded therebyis known to be the result of accelerations of the wall of the chest 12.These signals which are a result of acceleration forces can beamplified, if desired, and may be quantitated in the apparatus 18.

The accelerometer 10 is capable of providing a signal or signals whichare a function of the precordial vibrations of the subject. A wave formmay be obtained which represents blood pressure conditions. Thus, theaccelerometer 10 is capable of providing a signal or signals which are afunction of the blood pressure of the subject.

Furthermore, the accelerometer 10 is capable of providing a signal orsignals which are a function of the condition of the heart of thesubject.

, It has been found that the output signals of an accelerometer such asthe accelerometer 10 have a direct relationship to signals obtained bythe use of an electrocardiograph or a sphygmomanometer or an instrumentwhich is inserted into the cardiovascular system or other instrumentsfor determining cardiovascular or physiological conditions.

FIG. 3 shows a typical waveform obtained by the apparatus of thisinvention and a typical waveform obtained by an electrocardiograph,during one heart beat of the subject. The subject used in obtaining eachwaveform was a canine. However, similar comparison waveforms areobtained when the subject is a human. The electrocardiograph revealsprimarilyelectrical activity of the heart, while apparatus of thisinvention reveals mechanical activity of the heart, i.e., muscularmovement of the heart.

With regard to the waveform in F IG. 3 which was obtained by apparatusof this invention, the portion of the waveform referred to as AB isassociated with the function of the atrium. The portion CD is associatedwith the function of the ventricle, and the portion E6 is believed to beassociated with the function of the aorta. The amplitude of the portionCD of the waveform is directly related to systolic blood pressure.

The accelerometer 10 thus may be employed as an instrument or device toprovide signals which are directly related to blood pressure, heartcondition, heart rate, or other cardiovascular conditions, orrespiration rate, or other physiological conditions.

Although the preferred embodiment of the device has been described, itwill be understood that within the purview of this invention variouschanges may be made in the form, details, proportion and arrangement ofparts, the combination thereof and mode of operation, which generallystated consist in a device capable of carrying out the objects setforth, as disclosed and defined in the appended claims.

The invention having thus been described, the following is claimed:

1. Apparatus for providing signals which are a function of precordialvibrations, comprising an accelerometer transducer of the type which isresistive, complete balanced bridge, unbonded strain gage, the

accelerometer'transducer being directionally sensitive and having areading of between one times the force of gravity and 6 times the forceof gravity, the accelerometer transducer being adapted to engage aportion of the chest of a subject, the accelerometer transducer having asignal output and primary response in a direction substantially normalto a given axis of the accelerometer transducer, the accelerometertransducer adapted to be positioned in engagement with the said portionof the chest of the subject so that the accelerometer transducer movesin a direction substantially normal to said given axis thereof duringheart action of the subject, means responsive to the signal output ofthe accelerometer transducer connected to the accelerometer transducerand sensing frequencies in the range of between 2 and 30 cycles persecond, the signal output being a function of the precordial vibrationsassociated with the chest and being a function of the heart action ofthe subject.

2. The method of determining precordial vibrations of a subject,comprising positioning an accelerometer transducer in engagement withthe chest wall of the subject in the region of the heart and determiningthe output of the accelerometer transducer, the accelerometer transducerbeing of the type known as resistive, complete balanced bridge, unbondedstrain gage, the accelerometer transducer having a primary responsewhich is a function of the movement thereof in a direction substantiallynormal to the chest wall with which the accelerometer transducer is inengagement, the accelerometer transducer producing an output signalwhich is within the range of between two and thirty cycles per secondand which is thus a function of the heart action of the subject.

3. The method of obtaining signals which are the function of the bloodpressure of a subject comprising positioning an accelerometer transducerin engagement with the chest wall of the subject adjacent the apex beatlocation, the accelerometer transducer being of the type known asresistive, complete balanced bridge, unbonded strain gage, there beingmovement of the chest wall in response to the heart action of thesubject, sensing the signal output of the accelerometer transducer whichis within the range of between 2 and 30 cycles per second and which thusis a function of the amplitude of said movement of the chest wall, themagnitude of movement of the chest wall at frequencies between 2 and 30cycles per second being directly related to the systolic blood pressureof the subject.

4. Apparatus for physiological investigation of a subject comprising:

an accelerometer transducer adapted to engage a chest portion of thesubject, the accelerometer transducer being of the resistive, completebalanced bridge, unbonded strain gage type, the accelerometer transducerhaving a primary response which is normal to a given axis thereof, theaccelerometer transducer adapted to be positioned in engagement with achest portion of a subject so that the accelerometer transducer moves ina direction substantially normal to said given axis thereof withmovement of said chest portion of the subject during heart action of thesubject, the accelerometer transducer producing an output signal whichis a function of said movement,

tion of the heart action of the subject. 5. The method of claim 2 inwhich the accelerometer transducer is positioned at the apex beatlocation of the chest wall of the subject. I

1. Apparatus for providing signals which are a function of precordialvibrations, comprising an accelerometer transducer of the type which isresistive, complete balanced bridge, unbonded strain gage, theaccelerometer transducer being directionally sensitive and having areading of between one times the force of gravity and 6 times the forceof gravity, the accelerometer transducer being adapted to engage aportion of the chest of a subject, the accelerometer transducer having asignal output and primary response in a direction substantially normalto a given axis of the accelerometer transducer, the accelerometertransducer adapted to be positioned in engagement with the said portionof the chest of the subject so that the accelerometer transducer movesin a direction substantially normal to said given axis thereof duringheart action of the subject, means responsive to the signal output ofthe accelerometer transducer connected to the accelerometer transducerand sensing frequencies in the range of between 2 and 30 cycles persecond, the signal output being a function of the precordial vibrationsassociated with the chest and being a function of the heart action ofthe subject.
 2. The method of determining precordial vibrations of asubject, comprising positioning an accelerometer transducer inengagement with the chest wall of the subject in the region of the heartand determining the output of the accelerometer transducer, theaccelerometer transdUcer being of the type known as resistive, completebalanced bridge, unbonded strain gage, the accelerometer transducerhaving a primary response which is a function of the movement thereof ina direction substantially normal to the chest wall with which theaccelerometer transducer is in engagement, the accelerometer transducerproducing an output signal which is within the range of between two andthirty cycles per second and which is thus a function of the heartaction of the subject.
 3. The method of obtaining signals which are thefunction of the blood pressure of a subject comprising positioning anaccelerometer transducer in engagement with the chest wall of thesubject adjacent the apex beat location, the accelerometer transducerbeing of the type known as resistive, complete balanced bridge, unbondedstrain gage, there being movement of the chest wall in response to theheart action of the subject, sensing the signal output of theaccelerometer transducer which is within the range of between 2 and 30cycles per second and which thus is a function of the amplitude of saidmovement of the chest wall, the magnitude of movement of the chest wallat frequencies between 2 and 30 cycles per second being directly relatedto the systolic blood pressure of the subject.
 4. Apparatus forphysiological investigation of a subject comprising: an accelerometertransducer adapted to engage a chest portion of the subject, theaccelerometer transducer being of the resistive, complete balancedbridge, unbonded strain gage type, the accelerometer transducer having aprimary response which is normal to a given axis thereof, theaccelerometer transducer adapted to be positioned in engagement with achest portion of a subject so that the accelerometer transducer moves ina direction substantially normal to said given axis thereof withmovement of said chest portion of the subject during heart action of thesubject, the accelerometer transducer producing an output signal whichis a function of said movement, receiver means electrically connected tothe accelerometer transducer and sensing signals in the frequency rangeof between 2 and 30 cycles per second, said receiver means thusfunctioning in accordance with the mechanical action of the heart of thesubject to provide signals which are a function of the heart action ofthe subject.
 5. The method of claim 2 in which the accelerometertransducer is positioned at the apex beat location of the chest wall ofthe subject.